MED19 Promotes The Development Of Hepatocellular Carcinoma By Regulating The AKT/mTOR Signaling Pathway

Objective: Hepatocellular carcinoma(HCC) is one of the most common malignant tumors,and the pathogenesis is still unclear.Mediator complex subunit 19(MED19)is a subunit of the Mediator and a multi-protein co-activator necessary for DNA transcription factor to induce RNA polymerase II transcription.This study integrated bioinformatics methods and in vitro experimental verification,aiming to reveal the role and mechanism of MED19 in HCC.Methods: We analyzed the differential expression of MED19 between tumors and adjacent normal tissues in TCGA database through online database TIMER 2.0.The expression of MED19 in HCC was detected by online database GEPIA,and the survival stage and prognosis of patients with MED19-related HCC were analyzed.The expression of MED19 between HCC and normal tissues was verified by immunohistochemistry(IHC).The correlation between MED19 and age,sex,weight,and race of patients was analyzed in HCC by online database UALCAN.Then,we used sh RNA knockdown HCC cell lines(Hep G2 and Huh7),and studied the effect of MED19 knockdown on the biological function of HCC cells through MTT test,clone formation test,transwell invasion and migration test,scratch test,Hoechst-33258 apoptosis detection,and flow apoptosis analysis.Based on the above experiments,we downloaded the original data of HCC in the TCGA database,used the R language(3.6.3)software packages “cluster Profiler”,“ggplot2”,“enrichplot” to perform single gene enrichment analysis on MED19,and used the online database CHIPBase v2.0 for verification.Based on this,we used western blot to study the upstream and downstream genes related to MED19 enrichment pathways in HCC.The correlation between MED19 and other genes in HCC was discussed by online database Linked Omics.The correlation between MED19 and immune infiltration in HCC was analyzed by TIMER 2.0.Results:The TIMER 2.0 database showed that compared with adjacent normal tissues,the expression of MED19 was significantly increased in tumors including breast cancer(BRCA),lung adenocarcinoma(LUAD),bladder urothelial carcinoma(BLCA),and HCC.Here,through GEPIA database analysis,we found that in HCC,the expression of MED19 in tumors was significantly higher than that in non-tumor tissues,and reached the highest in stage III of cancer stage.The high expression of MED19 was related to overall survival and disease-free survival.Our IHC results also showed that the expression of MED19 in HCC was significantly higher than that in paracancerous tissues.Through the analysis of UALCAN database,we found that the expression of MED19 in HCC was not only related to the sample type,but also related to the patient’s race,age,sex,body grade,lymph node metastasis status,TP53 mutation status,and tumor histology.The cell functional experiments showed that after MED19 knockdown,the proliferation,migration,and invasion abilities of HCC cell lines were significantly inhibited,and the ability of apoptosis was significantly increased.TCGA database analysis showed that MED19 was positively correlated with AKT and mTOR.Western blot showed that MED19 knockdown significantly decreased the expression of p-AKT,p-mTOR and p-p70S6K1,but increased the expression of p-4EBP1.After used AKT agonist SC79,the AKT/mTOR pathway in HCC was partially restored.Through the Linked Omics database,we showed the genes that are positively or negatively related to MED19 in HCC.Conclusions: MED19 promotes the occurrence and development of HCC through AKT/mTOR signaling pathway.As a potential biomarker for the diagnosis of HCC,it may represent the potential therapeutic target of HCC.